Agentic Resource Discovery vs llms.txt
They answer different questions: Agentic Resource Discovery is a step 1 (Discover) standard, llms.txt step 4 (Read), so they are not substitutes.
| Agentic Resource Discovery ARD | llms.txt | |
|---|---|---|
| Lifecycle step | 1 Discover: What is here, and where? | 4 Read: Give me the content |
| Answers | Where are an organization's discoverable agentic resources (MCP servers, A2A agents, skills, registries), and how can they be found by search rather than pre-installed one at a time? | Where can an agent find a concise, curated map of a site's content, written for language models rather than browsers? |
| Governed by | Authored by individuals at Google, Microsoft and Hugging Face (Junjie Bu, R.V. Guha, Shaun Smith); published as an open GitHub project (ards-project/ard-spec) with no formal standards body yet; contributions acknowledged from AWS, Cisco, Databricks, GitHub, GoDaddy, Nvidia, Salesforce and Snowflake | Jeremy Howard / Answer.AI; maintained as an open proposal in the AnswerDotAI/llms-txt GitHub repository with a public Discord for implementation discussion |
| Status (issuer's words) | Proposal | "This is v2 of the proposal" — explicitly a community proposal open for input, not a standards-track document |
| Phase | draft | draft |
| Version | v0.91 (2026-08-26) | v2 (2026-08) |
| Form / transport | well-known file | well-known file |
| Found at | /.well-known/ard.json | /llms.txt (or /<path>/llms.txt, e.g. /docs/llms.txt) |
| Adoption | observed — agenticresources.dev own probe, 2026-09-04 | claimed — Rankability (Tranco top-1000, June 2026: 8.7%) and SE Ranking (~300,000 domains analyzed: 10.13%) — independent third-party publisher-side counts, not our own probe |
| Evidence | 2 verified, 2 reported | 4 verified, 4 reported |
| Primary use case | Let agents discover my API or service | Serve readable content to agents |
| Last verified | 2026-10-22 (current) | 2026-10-22 (current) |
| Specification | https://raw.githubusercontent.com/ards-project/ard-spec/main/spec/ard.md | https://llmstxt.org |
When to use which
- Choose Agentic Resource Discovery when your question is “Where are an organization's discoverable agentic resources (MCP servers, A2A agents, skills, registries), and how can they be found by search rather than pre-installed one at a time?” and you accept its maturity: phase draft, adoption observed (agenticresources.dev own probe, 2026-09-04).
- Choose llms.txt when your question is “Where can an agent find a concise, curated map of a site's content, written for language models rather than browsers?” and you accept its maturity: phase draft, adoption claimed (Rankability (Tranco top-1000, June 2026: 8.7%) and SE Ranking (~300,000 domains analyzed: 10.13%) — independent third-party publisher-side counts, not our own probe).
Read the full articles
- Agentic Resource Discovery: Where are an organization's discoverable agentic resources (MCP servers, A2A agents, skills, registries), and how can they be found by search rather than pre-installed one at a time?
- llms.txt: Where can an agent find a concise, curated map of a site's content, written for language models rather than browsers?